Lots of choices, but it all comes down to personal preference. I would search this site for some aquariums that you find appealing and and try to emulate it in with your own touch.
As far as wood, the Manzanita branches always look nice and natural in planted aquariums. Tie some moss or java fern to the branches for a more natural look. Very attractive.
For rocks, you could look into acquiring some Seiryu Stone. These rocks have a unique look to them that resembles miniature mountains. Many people just tastefully place several of these to create a "mountain range" (Iwagumi style aquascape) and then plant a low carpet plant throughout the tank, like this here: http://www.aquaticplantcentral.com/f...tainscape.html
For substrate, I guess that depends what you plan to do with your Betta. Some Substrate like ADA Aqua Soil Amazonia will create an ammonia spike which will likely kill your fish. Eco-Complete, is a good planting substrate that does not cause an ammonia spikes. Eco-Complete also has the added benefit of not needing to be rinsed and rinsed like Flourite does. For eco-complete, a single 20 lb bag should work for a 10 gallon aquarium.
Sounds like you want a plan before you proceed, which is good. I would suggest you simply google "Planted Aquarium" and look at all the images for inspiration.
Not sure I answered your questions or provided any useful information, but its really hard to know what appeals to you. We all have different tastes in the aquascape, plants, etc. Want proof, just look at all the different tanks of the members here.